MAMMALIA. 287 



is smooth at first, but raised into prominent longitudinal ridges 

 near the end. 



The following large glands are connected with the alimentary 

 canal salivary glands, liver, pancreas, and rectal glands. 



Four pairs of salivary glands open into the mouth-cavity, 

 parotid, submaxillary, sublingual, and infra-orbital. 



(1) The parotid glands are irregular pinkish masses, extending, on each 

 side, from the origin of the pinna to the higher end of the mandible. From 

 each a delicate (Stenson's) duct runs forwards just below the skin, turns 

 inwards, and opens into the side of the mouth-cavity opposite the last 

 upper molar. (2) The sub-maxillary glands are oval and compact bodies, 

 of reddish colour, lying near together between the rami of the mandible, 

 in front of the larynx. A delicate (Wharton's) duct runs from the outer 

 side of each to the floor of the mouth, in front of the tongue. (3) The small 

 red sub-lingual glands are elongated and flat. They lie in front of and 

 above the sub-maxillary glands among the muscles of the tongue. (4) The 

 infra-orbital glands are irregular and lobulated. They lie, one on each side 

 in front of and below the eye, partly within the orbit. A duct runs down- 

 wards from each and opens into the side of the mouth-cavity, opposite the 

 last upper premolar. 



The liver is a very large reddish-brown organ, closely applied 

 to the concave abdominal side of the diaphragm in front, and 

 largely overlapping the stomach behind. 



Right and left halves may be distinguished in the liver. The former is 

 divided into two lobes, right central, and caudate, hollowed out for, and 

 abutting against, the right kidney. The left half is divided into three lobes, 

 left central, left lateral, and the very small Spigelian, fitting into the an- 

 terior concavity of the stomach. A pear-shaped, thin-walled gall-bladder 

 lies in a slit on the posterior surface of the right central lobe. From it a 

 short cystic duct opens into the bile-duct, a small tube formed by the union 

 of hepatic ducts from the various liver-lobes, and opening into the duodenum 

 a little way beyond the pylorus. 



The pancreas is not compact as -in the frog and pigeon, but 

 diffuse i.e., made up of numerous scattered lobules. These 

 resemble small masses of fat, and are found in the mesentery 

 between the limbs of the U formed by the duodenum. Delicate 

 ducts proceed from the various lobules, and by their successive 

 unions the pancreatic duct is formed, which opens into the distal 

 limb of the duodenum, about 3 inches from the bend. 



The rectal glands are two compact elongated bodies lying 

 alongside and above the rectum near its termination, and opening 

 into it. 



The alimentary canal is lined as usual by mucous membrane. 



